Poor Idling
High Idle Speed
- Check Engine Control Module (ECM) power source and backup power source circuit. See ENGINE CONTROL MODULE POWER SOURCE CIRCUIT under COMPUTERIZED ENGINE CONTROLS in appropriate SYSTEM & COMPONENT TESTING article and DTC P0560: SYSTEM VOLTAGE under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.
- On Corolla (A/T ) and Matrix (A/T ), check park/neutral position switch. See PARK/NEUTRAL POSITION SWITCH under ENGINE SENSORS & SWITCHES in appropriate SYSTEM & COMPONENT TESTING article.
- Check A/C signal. A/C signal may also be referred to as A/C switch signal or compressor circuit. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
- On MR2 with sequential manual transaxle, check throttle body and components for Electronic Throttle Control System (ETCS). See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. Models with sequential manual transaxle may be identified by the shift lever pattern which consists of "R", "N", "S" and "+" in place of the conventional type shift lever pattern and no clutch pedal is used.
- On Corolla and Matrix, check ISC valve circuit. See DTC P0505: IDLE CONTROL SYSTEM MALFUNCTION under DIAGNOSTIC TESTS in SELF DIAGNOSTICS - COROLLA & MATRIX article.
- On MR2 (with standard M/T), check IAC valve circuit. See DTC P0505 & P0511: IDLE AIR CONTROL MALFUNCTION under DIAGNOSTIC TESTS in SELF DIAGNOSTICS - MR2 article.
- On RAV4, check IAC valve circuit. See DTC P0505: IDLE CONTROL SYSTEM MALFUNCTION under DIAGNOSTIC TESTS in SELF DIAGNOSTICS - RAV4 article.
Low Idle Speed
- On Camry (except Solara), Corolla, Matrix, MR2 and RAV4 models, check injector circuit. See DTC P0300: RANDOM/MULTIPLE CYLINDER MISFIRE DETECTED under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.
- Check Engine Control Module (ECM) power source and backup power source circuit. See ENGINE CONTROL MODULE POWER SOURCE CIRCUIT under COMPUTERIZED ENGINE CONTROLS in appropriate SYSTEM & COMPONENT TESTING article and DTC P0560: SYSTEM VOLTAGE under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.
- Check A/C signal. A/C signal may also be referred to as A/C switch signal or compressor circuit. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
- On all models, check fuel pump control circuit. See FUEL PUMP CONTROL CIRCUIT under COMPUTERIZED ENGINE CONTROLS in appropriate SYSTEM & COMPONENT TESTING article or on some models, see DTC P0230: FUEL PUMP PRIMARY CIRCUIT under DIAGNIOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.
- On MR2 with sequential manual transaxle, check throttle body and components for Electronic Throttle Control System (ETCS). See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. Models with sequential manual transaxle may be identified by the shift lever pattern which consists of "R", "N", "S" and "+" in place of the conventional type shift lever pattern and no clutch pedal is used.
- On Corolla and Matrix, check ISC valve circuit. See DTC P0505: IDLE CONTROL SYSTEM MALFUNCTION under DIAGNOSTIC TESTS in SELF DIAGNOSTICS - COROLLA & MATRIX article.
- On MR2 (with standard M/T), check IAC valve circuit. See DTC P0505 & P0511: IDLE AIR CONTROL MALFUNCTION under DIAGNOSTIC TESTS in SELF DIAGNOSTICS - MR2 article.
- On RAV4, check IAC valve circuit. See DTC P0505: IDLE CONTROL SYSTEM MALFUNCTION under DIAGNOSTIC TESTS in SELF DIAGNOSTICS - RAV4 article.
Rough Idle
- On Camry (except Solara) and MR2 models, check ignition coils with ignitor assemblies. See DTC P0351: IGNITION COIL PRIMARY/SECONDARY CIRCUIT under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.
- On Corolla, Matrix and RAV4 models, check ignition coils with ignitor assemblies. See DTC P1300: IGNITOR CIRCUIT MALFUNCTION under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.
- On Camry (except Solara), Corolla, Matrix, MR2 and RAV4 models, check injector circuit. See DTC P0300: RANDOM/MULTIPLE CYLINDER MISFIRE DETECTED under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.
- On all models, check fuel pump control circuit. See FUEL PUMP CONTROL CIRCUIT under COMPUTERIZED ENGINE CONTROLS in appropriate SYSTEM & COMPONENT TESTING article. On some models, see DTC P0230: FUEL PUMP PRIMARY CIRCUIT under DIAGNIOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.
- On vehicles with sequential manual transaxle, check throttle body and components for Electronic Throttle Control System (ETCS). See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. Models with sequential manual transaxle may be identified by the shift lever pattern which consists of "R", "N", "S" and "+" in place of the conventional type shift lever pattern and no clutch pedal is used.
- On Corolla and Matrix, check ISC valve circuit. See DTC P0505: IDLE CONTROL SYSTEM MALFUNCTION under DIAGNOSTIC TESTS in SELF DIAGNOSTICS - COROLLA & MATRIX article.
- On MR2 (with standard M/T), check IAC valve circuit. See DTC P0505 & P0511: IDLE AIR CONTROL MALFUNCTION under DIAGNOSTIC TESTS in SELF DIAGNOSTICS - MR2 article.
- On RAV4, check IAC valve circuit. See DTC P0505: IDLE CONTROL SYSTEM MALFUNCTION under DIAGNOSTIC TESTS in SELF DIAGNOSTICS - RAV4 article.
- On all models, check engine compression and spark plugs. See MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
- On Camry (except Solara) models, check MAF meter assembly. See DTC P0100: MASS OR VOLUME AIR FLOW CIRCUIT under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.
Hunting & Surging
- On Camry (except Solara), Corolla, MR2 and RAV4 models, check spark plugs. Replace as necessary.
- Check Engine Control Module (ECM) power source and backup power source circuit. See ENGINE CONTROL MODULE POWER SOURCE CIRCUIT under COMPUTERIZED ENGINE CONTROLS in appropriate SYSTEM & COMPONENT TESTING article and DTC P0560: SYSTEM VOLTAGE under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.
- On all models, check fuel pump control circuit. See FUEL PUMP CONTROL CIRCUIT under COMPUTERIZED ENGINE CONTROLS in appropriate SYSTEM & COMPONENT TESTING article or on some models, see DTC P0230: FUEL PUMP PRIMARY CIRCUIT under DIAGNIOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.
- On MR2 with sequential manual transaxle, check throttle body and components for Electronic Throttle Control System (ETCS). See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. Models with sequential manual transaxle may be identified by the shift lever pattern which consists of "R", "N", "S" and "+" in place of the conventional type shift lever pattern and no clutch pedal is used.
- On Corolla and Matrix, check ISC valve circuit. See DTC P0505: IDLE CONTROL SYSTEM MALFUNCTION under DIAGNOSTIC TESTS in SELF DIAGNOSTICS - COROLLA & MATRIX article.
- On MR2 (with standard M/T), check IAC valve circuit. See DTC P0505 & P0511: IDLE AIR CONTROL MALFUNCTION under DIAGNOSTIC TESTS in SELF DIAGNOSTICS - MR2 article.
- On RAV4, check IAC valve circuit. See DTC P0505: IDLE CONTROL SYSTEM MALFUNCTION under DIAGNOSTIC TESTS in SELF DIAGNOSTICS - RAV4 article.